Abstract

The present study consists of the simulation of two loss of coolant accidents, LOCA 6" and LOCA 2", in one of the residual heat removal system (RHR) lines outside the containment, using the thermal-hydraulic code RELAP5/MOD3.2.

Both transients have been simulated on a typical three loop, Westinghouse design, pressurized water reactor plant working under shutdown conditions.

The study was focused on the simulation of the most important thermal-hydraulic parameters in order to check the validity of the success criteria assumed in the plant probabilistic safety analysis (PSA) under shutdown conditions. Also to analyze the code capability for simulating shutdown conditions was of interest in this study.

As a result of this study, it can be concluded that the main thermal-hydraulic plant features follow what is foreseen in the plant PSA, although it can not be assured that the values reached are the correct ones due to the lack of experimental data.